1. Field of the Invention
The present invention relates to an IC card having an LSI such as a microprocessor, a memory or the like built therein, and more particularly to an IC card in which the built-in LSI is extremely thin.
2. Description of the Prior Art
In general, an IC card is a plastic card which comprises a microprocessor and a memory therein and takes the size of a credit card (85.5.times.54.times.0.76 mm). The IC card is superior in capacity of memory, security and the like, as compared with a magnetic tape which is currently mainstream. Therefore, it is expected that the IC card will become mainstream in the coming generation.
As shown in FIG. 5, the IC card has an IC module 102 fitted into a concave portion of a card body 101. The IC module 102 has the structure shown in FIG. 6 generally, in which an LSI chip 103 is provided in the concave portion on the back face of a PC substrate 104, electrodes of the LSI chip 103 are bonded to terminals 105 on the back face of the PC substrate 104 by a wire to conduct to external connecting terminals 106 on the surface of the IC module 102 and further the LSI chip 103 is molded by a resin 107.
As described above, the card body 101 must have a thickness of 0.76 mm (a tolerance of .+-.0.08 mm). For this reason, it is required to use the LSI chip which is made by abrading an LSI chip 0.5 mm thick for general electronic equipment to have a thickness of about 0.3 mm.
However, the LSI chip 103 of which thickness is about 0.3 mm has a fragile silicon substrate. Therefore, even if the strength is enhanced by the mold resin 107, the LSI chip 103 may be easily broken by external stress in an actual using environment and is not reliable.
The IC card will have the same value as that of money if it is widespread. Therefore, the above-mentioned problem can not be ignored and should be solved in its early stages.